The synthesis of polymethacrylates with terminal functional groups and, in particular, with terminal hydroxyl groups, was attempted in various ways in recent years, since such compounds are of particular interest for the preparation of block copolymers, for example, for the preparation of polyesters or polyurethanes.
In particular, attempts have been made to obtain such polymethacrylate glycols by way of group transfer polymerization. However, extremely high purity of the reagents used and the strict exclusion of air moisture are a prerequisite for carrying out the group-transfer reaction. By using initiators, which are listed in Houben-Weyl, Methoden der organischen Chemie (Methods of Organic Chemistry), volume E 20/Part 1, Table 18, pages 158 ff. and which can be synthesized only at great cost, only monofunctional polymers are obtained, which have a narrow molecular weight distribution. The synthesis of .alpha., .omega. difunctional polymers by means of this, so far, only method is not possible or possible only incompletely at great expense (D. Y. Sogah and O. W. Webster, J. Polym. Sci., Polym. Lett. Ed. 21, 927 (1983)).
Another way of synthesizing .alpha., .omega.-terminated polymethacrylates was recently described using thiuram disulfides, which contain the hydroxyethyl groups. The synthesis was carried out according to the so-called "Iniferter" technique (initiator, transfer agent, terminator). Admittedly, the products obtained had a functionality, which comes close to the desired 2. However, the products, due to their high sensitivity to hydrolytic and thermal effects, can be used only to a limited degree (C. P. Reghunadham et al., J. Polymer Sci., part A: Pol. Chem. 27, 1795 (1989)).
The present invention is concerned with the technical problem of synthesizing such .alpha., .omega.-polymethacrylate glycols readily, the content of polymethacrylates with a functionality of less than 2 or more than 2 being, as far as possible, 0.